Do any smartphones play avi files?

Avi is a video container - as such it can be all sorts of stuff.
You won't find an AVI-certified device, because there are many many variations; but as matt says, any Android can play MOST Avi videos either natively, or with an app a la MXVideo or RockPlay or or or...
iPhones cannot play Avi variants natively, but GoodPlayer etc do the job. Most newer Symbian phones and BlackBerry phones can at least play some Avi9 files. It's a bit trial and error... I had bad luck with all smartphone OSs - some files are encoded so oddly that only a mighty desktop player can handle them.
If a file fails, just reconvert to a more common format.

Avi is a video container - as such it can be all sorts of stuff.
You won't find an AVI-certified device, because there are many many variations; but as matt says, any Android can play MOST Avi videos either natively, or with an app a la MXVideo or RockPlay or or or...
iPhones cannot play Avi variants natively, but GoodPlayer etc do the job. Most newer Symbian phones and BlackBerry phones can at least play some Avi9 files. It's a bit trial and error... I had bad luck with all smartphone OSs - some files are encoded so oddly that only a mighty desktop player can handle them.
If a file fails, just reconvert to a more common format.